Mercedes Power Unit Hardware & Software

[saviour stivala]

I got nothing back-to-front as I was as I stated ‘quoting trendy trend – fithecnical net forum 2006’. Read 3rd from top post (17 sept) on this page. According to trendy trend he was talking from actual personal dyno testing experience on the effects throttle bodies in front of turbo compressors on road going ICE.
Further= on road going turbocharged ICE compressor throttle bodies in front of compressor are used in conjunction with normal throttle bodies on ICE. They were added to reduce turbo-lag by inducing partial vacuum. This did two things:- firstly it allows the turbo to spin longer at higher rpm because of the reduced pumping losses. Secondly :- the partial vacuum helped accelerate the air through the impeller, rather then just relying on the impeller to pull-it through. The main throttle bodies (ICE) were retained because the response time to driver input is faster.

[noname]

‘’Swirl caused by angling the movable vanes will actually only improve efficiency at only one point on the map. Generally the effects are detrimental to the efficiency and linear flow is desirable.’’

You got it back to front. Non-rotating inlet flow will give best efficiency at only one point (or line of points) on the map. Movable vanes will give best efficiency at every point on the map and will NEVER be detrimental.
https://www.airbestpractices.com/techno ... efficiency

VIGVs are used to extend compressor range, as they allow to move surge line to the left.

Map gets wider, but efficiency and performance during off-design operation is reduced.

F1 compressors can benefit from VIGV, but it is more because inlet designs are compromised by PU packaging. VIGV helps to recover losses in the inlet duct(s).

[chaoticflounder]

I got nothing back-to-front as I was as I stated ‘quoting trendy trend – fithecnical net forum 2006’. Read 3rd from top post (17 sept) on this page. According to trendy trend he was talking from actual personal dyno testing experience on the effects throttle bodies in front of turbo compressors on road going ICE.
Further= on road going turbocharged ICE compressor throttle bodies in front of compressor are used in conjunction with normal throttle bodies on ICE. They were added to reduce turbo-lag by inducing partial vacuum. This did two things:- firstly it allows the turbo to spin longer at higher rpm because of the reduced pumping losses. Secondly :- the partial vacuum helped accelerate the air through the impeller, rather then just relying on the impeller to pull-it through. The main throttle bodies (ICE) were retained because the response time to driver input is faster.

Do you know for certain they’re using throttle bodies? Technically speaking it represents an efficiency loss in the system as it is a method of controlling engine rpm that works by increasing pumping losses on the intake.

[saviour stivala]

Out of the four different power unites used the only one I actually seen was the Mercedes. I do not remember the time but it was recently and on this forum, there was a Mercedes power unit photo showing the turbo compressor intake throttling system with all five vanes closed and marked one to five.

[gruntguru]

I got nothing back-to-front as I was as I stated ‘quoting trendy trend – fithecnical net forum 2006’. Read 3rd from top post (17 sept) on this page. According to trendy trend he was talking from actual personal dyno testing experience on the effects throttle bodies in front of turbo compressors on road going ICE.
Further= on road going turbocharged ICE compressor throttle bodies in front of compressor are used in conjunction with normal throttle bodies on ICE. They were added to reduce turbo-lag by inducing partial vacuum. This did two things:- firstly it allows the turbo to spin longer at higher rpm because of the reduced pumping losses. Secondly :- the partial vacuum helped accelerate the air through the impeller, rather then just relying on the impeller to pull-it through. The main throttle bodies (ICE) were retained because the response time to driver input is faster.

When you quote another source you should:
a) At least say so.
b) Preferrably use the quote button (4th from the left).
c) Better still provide a link to the source so anyone can read the full context. This is very easy to do on this forum.

I do understand the turbo response benefits of an upstream throttle plate. I have personal experience having installed hundreds of "Draw through" turbo systems in the 1980s. The radial vane throttling system has the additional benefits I mentioned.

@ no name there are further benefits when the compressor itself is designed in the knowledge that the vane inducer is present. This is not the same as adding a vane inducer to a compressor that was designed for a wide efficiency characteristic with the vanes.

[johnny comelately]

Proposal: Rename this forum to Technical Chinese Whispers

[johnny comelately]

My whisper says: after much calculation and heavy discussion which took 8 seconds, this was arrived at. Admittedly for a non-offthrottle situation
My archaic brain cannot think of any throttles on F1 engines before the turbo, if anyone has a picture of such I would be interested

[saviour stivala]

At that time (80’s) and before the general believe was that there was no such thing as a good ‘’draw-through’’ simply because putting a carburetor in front of a turbo is a sizable restriction.
The efficiency benefits that apples to a constant speed running centrifugal industrial stationery air compressor does not automatically apply to road going ICE turbocharger compressor.
At least for me nothing beats Australian whispers for changing a piece of information when passed over.

[PlatinumZealot]

Closing the movable vanes when driver lifts throttle will increase turbo rpm for a given turbine exhaust flow because with no airflow the compressor have less work to do, when driver returns on throttle the turbo higher rpm will eliminate turbo lag.

Not really..
See previous post, where I said if you close of the compressor (assuming the electrical machine is off) you can over-speed the turbocharger. And Why would you want the compressor not to do any work?

Lets say you manage to rotate the turbo charger faster without overspeed, and you now introduce air again... if there is no air in the engine, what will turn the compressor? You can't just lock off all the air to the engine and expect there compressor to turn faster after that.

Again, most liklely purpose is to introduce swirl to make the compressor more efficient... There could be an argument for some sort of surge prevention too.. might even actually open the blades and load the compressor more come to think of it.. I thought you were talking about it from that angle.

[PlatinumZealot]

My whisper says: after much calculation and heavy discussion which took 8 seconds, this was arrived at. Admittedly for a non-offthrottle situation
My archaic brain cannot think of any throttles on F1 engines before the turbo, if anyone has a picture of such I would be interested
https://images-wixmp-ed30a86b8c4ca88777 ... E7RI1fAWcU

You would be surprised!!

[johnny comelately]

My whisper says: after much calculation and heavy discussion which took 8 seconds, this was arrived at. Admittedly for a non-offthrottle situation
My archaic brain cannot think of any throttles on F1 engines before the turbo, if anyone has a picture of such I would be interested
https://images-wixmp-ed30a86b8c4ca88777 ... E7RI1fAWcU

You would be surprised!!

https://s1.cdn.autoevolution.com/images ... 7344-7.jpg

The M12's major shortcoming as a Formula One engine was its lack of throttle response due to turbo lag
"https://en.wikipedia.org/wiki/BMW_M12"
and the whispers continue

[Tommy Cookers]

... putting a carburetor in front of a turbo is a sizable restriction.....

why ?

[Clubman1d]

Out of the four different power unites used the only one I actually seen was the Mercedes. I do not remember the time but it was recently and on this forum, there was a Mercedes power unit photo showing the turbo compressor intake throttling system with all five vanes closed and marked one to five.

The thing is, looking at the actuation mechanism, the colar, it isn't possible for them to be closed, the maximum movement they seem to present is around 45 degrees.

Even if they do manage to close, it doesn't seem the vane design covers all the frontal area.

[saviour stivala]

Out of the four different power unites used the only one I actually seen was the Mercedes. I do not remember the time but it was recently and on this forum, there was a Mercedes power unit photo showing the turbo compressor intake throttling system with all five vanes closed and marked one to five.

The thing is, looking at the actuation mechanism, the colar, it isn't possible for them to be closed, the maximum movement they seem to present is around 45 degrees.

Even if they do manage to close, it doesn't seem the vane design covers all the frontal area.

The photo I referred too which shows the vanes numbered one to five shows the vanes totally closed, of course the engine in that photo is not running, but that shows that in fact that they can close as in the photo. Now let us calmly dialogue this interesting subject, while keeping to the subject at hand. mine and my opinion only, first of all I believe that placing anything in front of the compressor air intake is in itself a restriction to that intake area. So the fact that they did not chose the camera iris system to throttle the intake which totally eliminates any intake restriction when fully open, means that they where willing to except the restriction of the five vane edges when fully open in front the turbo intake, for in turn getting some swirl. Although for the compressor to get some vacuum for the purpose of partially unloading the compressor and so maintain higher rpm, the vanes does not need to fully close, they only need start restricting the intake. Which leaves only the fully closed position question. Why fully close?. When driver goes off throttle (lifts) momentarily as it my be, the ICE throttles are fully closed. So no air is entering the cylinders, in this off throttle situation if the compressor intake throttle is not closed, a pop-up valve will have to be used. Further back in the thread, putting one’s hand on the intake of a vacuum cleaner nozzle example was given to unload the vacuum cleaner motor to spin faster.

[Clubman1d]

Out of the four different power unites used the only one I actually seen was the Mercedes. I do not remember the time but it was recently and on this forum, there was a Mercedes power unit photo showing the turbo compressor intake throttling system with all five vanes closed and marked one to five.

The thing is, looking at the actuation mechanism, the colar, it isn't possible for them to be closed, the maximum movement they seem to present is around 45 degrees.

Even if they do manage to close, it doesn't seem the vane design covers all the frontal area.

The photo I referred too which shows the vanes numbered one to five shows the vanes totally closed, of course the engine in that photo is not running, but that shows that in fact that they can close as in the photo. Now let us calmly dialogue this interesting subject, while keeping to the subject at hand. mine and my opinion only, first of all I believe that placing anything in front of the compressor air intake is in itself a restriction to that intake area. So the fact that they did not chose the camera iris system to throttle the intake which totally eliminates any intake restriction when fully open, means that they where willing to except the restriction of the five vane edges when fully open in front the turbo intake, for in turn getting some swirl. Although for the compressor to get some vacuum for the purpose of partially unloading the compressor and so maintain higher rpm, the vanes does not need to fully close, they only need start restricting the intake. Which leaves only the fully closed position question. Why fully close?. When driver goes off throttle (lifts) momentarily as it my be, the ICE throttles are fully closed. So no air is entering the cylinders, in this off throttle situation if the compressor intake throttle is not closed, a pop-up valve will have to be used. Further back in the thread, putting one’s hand on the intake of a vacuum cleaner nozzle example was given to unload the vacuum cleaner motor to spin faster.

After reading about it, Garret doesn't make a secret out of it, you're absolutely right.
They close "fully", increasing the turbo spin speed and help keeping it spinning.
I did find a picture witch I believe might be from an older Mercedes engine.